Why Does My Kidney Hurt When I Run

Flank Pain While Running: An Overview

Have you ever experienced discomfort or pain in your lower back or side while running, wondering “why does my kidney hurt when I run?” You’re not alone. Many runners have encountered this issue at some point in their running journey. This article aims to shed light on the potential causes and offer guidance on addressing this concern.

Anatomy and Function of the Kidneys

The kidneys are a pair of vital organs located in the lower back, just above the waist. Each kidney is about the size of a fist and plays a crucial role in maintaining the body’s overall health. The primary function of the kidneys is to filter waste and excess fluids from the blood, producing urine that is then transported to the bladder for elimination. Additionally, kidneys help regulate electrolyte levels, maintain blood pressure, and produce hormones that stimulate red blood cell production.

Common Causes of Kidney Pain During Running

Several factors can contribute to kidney pain while running. Dehydration, kidney stones, and muscular issues are among the most prevalent causes. Understanding these underlying causes can help you address the problem and find relief.


Dehydration occurs when the body loses more fluids than it takes in, leading to an imbalance that can negatively impact overall health and performance. When running, dehydration can cause the kidneys to work harder, potentially leading to discomfort or pain. To prevent dehydration, ensure you consume enough fluids before, during, and after your runs. Aim for 16 to 20 ounces of water two to three hours before your run, 8 to 12 ounces of water 15 to 30 minutes before your run, and 4 to 8 ounces of water every 15 to 20 minutes during your run. Additionally, consider incorporating electrolyte-rich drinks or snacks to help maintain a healthy fluid balance.

Kidney Stones

Kidney stones are small, hard mineral deposits that can form in the kidneys and cause severe pain when passed through the urinary tract. While kidney stones may not always be related to running, the physical stress of running can exacerbate the discomfort. If you suspect you have kidney stones, consult a medical professional for proper diagnosis and treatment. To minimize the risk of developing kidney stones, maintain a well-balanced diet, stay hydrated, and avoid excessive consumption of high-oxalate foods such as spinach, beets, and chocolate.

Muscular Issues

Sometimes, the pain experienced during or after running may not be related to the kidneys at all. Muscular issues, such as strained or inflamed back muscles, can mimic kidney pain. To differentiate between kidney pain and muscular discomfort, pay attention to the location of the pain and any accompanying symptoms. If the pain is localized to the muscles, stretching, foam rolling, or applying heat or cold therapy may provide relief. If the pain persists or worsens, consult a medical professional for further evaluation.

How to Differentiate Kidney Pain from Other Running-Related Discomforts

Kidney pain while running can sometimes be confused with other common running-related discomforts, such as side stitches or muscle cramps. Understanding the differences between these issues can help you accurately identify the source of your pain and seek appropriate treatment.

Side Stitches

Side stitches, also known as exercise-related transient abdominal pain (ETAP), are a common issue for runners. They typically manifest as a sharp, stabbing pain on either side of the abdomen, often under the lower ribcage. Side stitches are usually caused by shallow breathing, eating too close to a run, or running in cold weather. To alleviate side stitches, try slowing down your pace, focusing on deep, rhythmic breathing, or gently pressing your fingers into the affected area.

Muscle Cramps

Muscle cramps, or charley horses, are involuntary contractions of muscles that can occur during or after running. While muscle cramps can affect any muscle, they are most common in the legs, particularly the calf muscles. Muscle cramps can be caused by various factors, including dehydration, electrolyte imbalances, muscle fatigue, or inadequate warm-up and cool-down routines. To prevent muscle cramps, ensure you stay hydrated, consume a balanced diet, and perform proper warm-up and cool-down exercises before and after your runs.

Additional Discomforts

Other running-related discomforts, such as hip or back pain, may sometimes be mistaken for kidney pain. To differentiate between these issues, consider the location of the pain and any accompanying symptoms. Hip or back pain is often localized to the lower back, hips, or buttocks, and may be accompanied by stiffness or reduced mobility. If you suspect you are experiencing hip or back pain, consult a medical professional for proper diagnosis and treatment.

The Importance of Proper Hydration and Nutrition

Maintaining proper hydration and nutrition is crucial for preventing kidney pain and ensuring optimal running performance. By following a few practical tips and guidelines, you can optimize your fluid and fuel intake to support your running goals and overall health.


Staying hydrated is essential for kidney function and overall health. To maintain proper hydration levels while running, consider the following:

  • Pre-hydrate: Drink 16 to 20 ounces of water two to three hours before your run and 8 to 12 ounces 15 to 30 minutes before your run.
  • Stay hydrated during your run: Consume 4 to 8 ounces of water every 15 to 20 minutes during your run. If your runs exceed one hour, consider incorporating an electrolyte-rich drink to help maintain a healthy fluid balance.
  • Rehydrate post-run: Drink 16 to 24 ounces of water for every pound lost during your run. Monitor your urine color, aiming for a pale yellow hue, which indicates proper hydration.


A well-balanced diet can help prevent kidney pain and support overall running performance. Focus on consuming a variety of nutrient-dense foods, including:

  • Fruits and vegetables: Aim for a variety of colors to ensure a broad range of vitamins and minerals. Opt for low-oxalate options, such as berries, melons, and cucumbers, to minimize the risk of kidney stones.
  • Lean proteins: Choose lean sources of protein, such as chicken, turkey, fish, and tofu, to support muscle repair and recovery.
  • Whole grains: Incorporate whole grains, such as brown rice, quinoa, and whole-wheat bread, for sustained energy and fiber.
  • Healthy fats: Consume healthy fats, such as avocados, nuts, seeds, and olive oil, to support cellular function and overall health.

Additionally, avoid excessive consumption of high-oxalate foods, such as spinach, beets, and chocolate, to minimize the risk of kidney stones.

When to Consult a Medical Professional

Preventive Measures and Long-Term Strategies

To minimize the risk of experiencing kidney pain while running, it’s essential to adopt preventive measures and long-term strategies that promote overall kidney health and running performance. By incorporating these practices into your training routine, you can reduce the likelihood of kidney discomfort and ensure a more enjoyable running experience.

Gradual Progression

When increasing your running distance, intensity, or frequency, make sure to do so gradually. Rapid increases in training volume can put additional stress on your kidneys, potentially leading to discomfort or pain. A general guideline is to increase your weekly mileage by no more than 10% to allow your body to adapt to the increased demands.

Strength Training

Incorporating strength training exercises into your routine can help improve your running performance and reduce the risk of kidney pain. Focus on strengthening your core, hips, and legs to maintain proper running form and reduce the strain on your kidneys and other supporting muscles. Exercises such as planks, squats, lunges, and bridges can be particularly beneficial.

Regular Medical Check-ups

Schedule routine medical check-ups to monitor your overall health and kidney function. Regular check-ups can help identify any potential issues early on, allowing for prompt treatment and prevention of more severe complications. If you have a history of kidney problems or other health concerns, consult your healthcare provider for personalized advice and recommendations.

Stay Hydrated

Maintaining proper hydration is crucial for kidney health and overall running performance. Staying hydrated helps your kidneys filter waste and excess fluids from your blood, reducing the risk of kidney pain and other complications. Aim to drink 16 to 20 ounces of water two to three hours before your run, 8 to 12 ounces 15 to 30 minutes before your run, and 4 to 8 ounces every 15 to 20 minutes during your run. After your run, replace the fluids you’ve lost by drinking 16 to 24 ounces of water for every pound lost.

Listen to Your Body

Pay attention to your body’s signals and respond accordingly. If you experience persistent or severe kidney pain, or if the pain is accompanied by other concerning symptoms, consult a medical professional for proper diagnosis and treatment. By listening to your body and addressing any issues promptly, you can maintain your running performance and overall health.

Real-Life Experiences and Case Studies

Understanding how others have dealt with kidney pain while running can provide valuable insights and reassurance for those experiencing similar issues. Here, we share real-life experiences and case studies of runners who have faced kidney pain, offering a glimpse into their challenges, solutions, and lessons learned.

Case Study 1: Dehydration and Kidney Pain

John, a 35-year-old avid runner, experienced sharp flank pain during a long run on a hot summer day. After consulting with his healthcare provider, he discovered that dehydration was the culprit. By increasing his fluid intake before, during, and after runs, as well as adding electrolytes to his hydration routine, John was able to prevent further kidney pain while running.

Case Study 2: Muscular Issues and Kidney Pain

Sarah, a 28-year-old marathoner, struggled with recurring kidney pain during her training sessions. After undergoing physical therapy and focusing on strengthening her core and hip muscles, she noticed a significant reduction in kidney pain. By maintaining a consistent strength training routine, Sarah has been able to run pain-free.

Case Study 3: Kidney Stones and Running

Mike, a 42-year-old recreational runner, was diagnosed with a kidney stone after experiencing severe flank pain during a run. Although he had to take a short break from running, he resumed his training routine after passing the kidney stone and consulting with his healthcare provider. By staying well-hydrated and maintaining a balanced diet, Mike has managed to prevent further kidney stone formation and related pain while running.

These real-life experiences demonstrate that kidney pain while running can be managed and often prevented with proper hydration, nutrition, strength training, and medical care. By learning from others’ challenges and solutions, runners can take proactive steps to ensure their running performance and overall health.